Matter, Atoms and Molecules RRB PYQ

NaCl is a correct representation of a compound formed by ionic bonding. Sodium loses one electron to form Na+, and Chlorine gains one electron to form Cl-. The electrostatic attraction between Na+ and Cl- makes the ionic bond.

Statement-I is true, because Ionic compounds have a rigid and brittle crystal lattice structure. When pressure is applied, the ions of the same charge are forced closer together, resulting in repulsive forces that cause the crystal to shatter. Statement-II is false, because ionic compounds typically have high melting and boiling points due to the strong electrostatic forces of attraction between the oppositely charged ions in their lattice structure, which require a significant amount of energy to overcome.

Soft drink and soda water bottles are sealed under high pressure in beverage industries to increase the solubility of carbon dioxide. Henry's Law states that the amount of a gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the surface of the liquid. By increasing the pressure inside the sealed bottle, more carbon dioxide molecules are forced into the liquid. When the bottle is opened, the pressure is released, the solubility of carbon dioxide decreases dramatically, and the dissolved gas rapidly escapes the solution.

Carbon has a valency of 4 due to the four electrons in its outermost shell. Needing four more electrons to complete the octet, carbon can form four covalent bonds. As the 6th element in the periodic table, carbon's electronic configuration is 2,4, with the last four being valence electrons that determine its bonding behavior.

Chlorine shows variable valency and forms several oxides. In chlorine heptoxide, Cl2O7, oxygen has valency 2. Therefore, seven oxygen atoms contribute a total combining capacity of 14, which is shared by two chlorine atoms; hence the valency of each chlorine atom with respect to oxygen is 7. Chlorine belongs to Group 17 of the periodic table and has seven valence electrons. It commonly exhibits oxidation states -1, +1, +3, +5 and +7. In Cl2O7, chlorine is in its highest oxidation state, +7.

Chlorine molecule displays a non-polar covalent bonding. In a nonpolar covalent bond, electrons are shared equally and there is no sharp dividing line between polar and nonpolar and as per thumb rule the Non polar covalent would be considered for if the electronegativity difference between bonding atoms is less than 0.5 and hence anything greater than this value will be considered for anything but nonpolar bond.

Silicon shows the property of catenation, i.e., the ability of an element to form covalent bonds with atoms of the same element and produce chains. Silicon forms hydrides containing chains of up to seven or eight silicon atoms, but these compounds are highly reactive. Carbon shows catenation to a much greater extent because the carbon-carbon bond is very strong and stable. Its small atomic size allows effective bonding, enabling the formation of long straight chains, branched chains and rings. Silicon-silicon bonds are comparatively weaker, which limits the length and stability of its chains.

The correct formula for the compound formed by tetravalent element X and divalent element Y is XY2. Since element X can form four bonds and element Y can form two, two Y atoms are needed to balance the four valence electrons of one X atom.

In this reaction, silver chloride (AgCl) breaks down into silver (Ag) and chlorine gas (Cl2) when exposed to ultraviolet light. This type of reaction, where a compound decomposes due to light, is known as photolytic decomposition. The chemical equation is: 2AgCl(s) → 2Ag(s) + Cl2(g).

Hydrogen Sulphide (H2S) is a colourless, toxic gas that smells like rotten eggs, which is a characteristic odour making it easily identifiable. It is naturally found in crude petroleum, natural gas, volcanic gases, and hot springs. Exposure to hydrogen sulphide in high concentrations can be hazardous to human health, potentially leading to respiratory issues and even death.